Two Most Remarkable Amoeba Men:Joseph Leidy (1823–1891) of Philadelphia andEugène Penard (1855–1954) of GenevaJohn O. Corliss1

P.O. Box 2729, Bala Cynwyd, PA 19004, USA

“How can life be tiresome so long as there is still a new rhizopod undescribed?” Joseph Leidy

Protist, Vol. 152, 69–85, May 2001 © Urban & Fischer Verlag http://www.urbanfischer.de/journals/protist

Joseph Leidy and Eugène Penard, early pioneersand experts without peer (in their times and stilltoday) in detailed study of the morphology and tax-onomy of the free-living rhizopod Sarcodina, sharedpossession of a great curiosity about and a lovingdevotion to these fascinating if oft-neglected pro-tists. But, otherwise, both the professional and per-sonal lives of these two individuals differed quitemarkedly. As we shall see, our pair of distinguishedgentlemen had little in common beyond their pas-sion and ability to carry out invaluable researches atthe microscopical “amoeba” level, no easy accom-plishment in the times of their work. Our debt tothem as outstanding biological scientists will endureforever, although – as dedicated naturalists – theynever achieved the fame and recognition accordedthe inspired experimentalists and conceptual theo-rists of their day and of all times since then … and,alas, they never shall. A further factor, which theyshare in being largely neglected today, is their lackof establishment of a school to follow in their scien-tific footsteps: both men were essentially loners,having neither students nor close colleagues asjoint-authors.

Thus the present article is offered, in part, as atribute to all such dedicated fact-finding workers ofthe past widely forgotten, today, following advent ofmore sophisticated (and often experimental) ap-

proaches to solution of many of our age-old biologi-cal problems.

Brief Historical Background

In the broad area of the systematics of species be-longing to major groupings of the Sarcodina sensulato (but mostly excluding, here – purposely – refer-ence to fossil and parasitic forms and most mem-bers of the Radiolaria), other principal workers – pre-decessors or contemporaries of Leidy and Penard –of the period stretching from early nineteenth toearly twentieth century deserve at least brief men-tion, with specific citation to several of their mainpublications: Archer (numerous scattered papers,not cited here, period 1866–1880), Awerinzew(1906), de Bary (1859 et seq.), Blochmann (1886),Bütschli (1880–1882), Carter (scattered works, notcited, period 1856–1870), Cash and Hopkinson(1905, 1909), Cash and Wailes (1919, 1921), Cash etal. (1915), Cienkowski (1863 et seq.), Claparède andLachmann (1858-1861), Dobell (1919), Dujardin(1841), Ehrenberg (1838), Greef (scattered papers,not cited, period 1866–1879), Haeckel (1878, 1894),Hertwig (1879), Hertwig and Lesser (1874), A. and G.Lister (1925), J. Müller (1858), Perty (1852, and ear-lier), Rhumbler (1903), Schaeffer (1916, 1920, 1926),Schewiakoff (1926), Schulze (1874), Wailes (1912,1913), and Wallich (scattered papers, not cited,years 1863–1875).

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From the above-mentioned 100-year period untilnearly the present, additional protistologists con-tributed heavily to further advances in understand-ing better the taxonomy of diverse sarcodinid taxa:Alexopoulos, Bardele, Bonnet, Bovee, the Cachons,Chardez, Chatton, Cushman, Decloître, Deflandre,De Saedeleer, Febvre, Febvre-Chevalier, Foissner,Grell, Grospietsch, Haynes, Heal, Hedley, Hollande,Hoogenraad, Jahn, Jepps, Jung, Kudo, Kühn, Lee,Loeblich, Ogden, Olive, Page, Patterson, Raper,Sawyer, Schönborn, Singh, Tappan, Trégouboff,Valkanov, and Vickerman: see references in Boveeand Jahn (1973), Corliss (1978–1979, 1992), andcontemporary protistological compendia such asLee et al. (1985, 2001) and Margulis et al. (1990).Seldom, however, are the publications of the aboveresearchers of the monographic proportions ofsome of those cited in the preceding paragraph, al-though the prodigious output of excellent system-atic and descriptive papers and reviews by threemodern workers – E. C. Bovee, K. G. Grell, and F. C.Page – warrant special recognition with regard tothe rhizopod amoebae overall. A bit earlier, a prolificexpert on the thecamoebae was G. Deflandre (seecitations in Deflandre 1953).

Today, as we enter the 21st century, there aresurely even fewer protistologists intensively devot-ing major research effort to amoeba morphologyand taxonomy than the scant one dozen of 25–30years ago, a figure that Bovee (in Bovee and Jahn1973) was justifiably lamenting as too low a number.

Incidentally, it is rather surprising that the amaz-ingly perceptive first observer of “little things,” A.Leeuwenhoek of Delft, never detected or describedan amoeba (except for one foraminiferan found in thestomach of a shrimp: see Corliss 1975) amongst theextensive collections of protists he examined withhis “glorified hand lens” in the late 1600s. It was wellinto the next century that Joblot (1718) gave us avery brief description of what we now know as theheliozoon Actinophrys sol and that Rösel von Rosen-hof (1755) published a paper on his celebrated “littleProteus”; and then still some 30 years after that be-fore the astute observations of O. F. Müller (1786) be-came available, a monograph including descriptionsof a (but very) few amoebae along with those ofmany other microscopic forms of life.

Early Life and Education of Leidy andPenard

Joseph Leidy (Fig. 1) was born in the heart ofPhiladelphia (PA, USA) on 9 September 1823. Likehis father and grandfather before him, he was a

“true-blue” Philadelphian and seldom traveled farfrom his beloved city throughout his lifetime. Hisgreat grandfather, John Jacob Leydig (as the sur-name was originally spelled in Germany), had emi-grated from Wittenberg to escape religious persecu-tion, arriving in Philadelphia in 1729 and settling on atract of 400 acres purchased from the well knownQuaker William Penn. John Jacob, interestinglyenough, was a brother of the great grandfather ofFranz Leydig [1821–1905], distinguished histologistand comparative anatomist of Würzburg and Bonnand a contemporary of Joseph, our American natu-ralist. And John Jacob’s wife was a sister of FrancisJoseph LeFebre, a marshal of Napoleon I and a peerof France.

Joseph Leidy’s mother died two years after givinghim birth; his father (a hatter by trade) soon (re)mar-ried, a cousin of his wife’s; and it is to his highly intel-ligent, cultured, and principled stepmother (Chris-tiana Mellick) that Leidy himself credits his stimulat-ing early home environment. Although German, acommon language in various parts of Pennsylvaniain those days, was spoken in the home, Christianainsisted on everyone’s practicing English as well;and, at her instigation, young Joseph, at age eight,

70 J. O. Corliss

Figure 1. Joseph Leidy, M.D. (1823–1891), in his mid-sixties (a couple of years before his demise). [Photo-graph from the author’s private collection]

was sent to a private day school where he began tolearn – while also taking other studies – Latin, Greek,and French, as well as English, all languages tostand him in good stead in later years.

Joseph was an able student but preferred study-ing nature directly rather than undergoing formal ed-ucation in a regular classroom setting. His avid cu-riosity about plants, animals, and minerals, com-bined with a natural talent in artistry, led to produc-tion (by age 10 and beyond) of notebooks filled withaccurate sketches of rocks and organisms encoun-tered in the wild, with the latter often labeled withtheir correct Latin names. On days and hours not re-quired to be in the schoolhouse, he preferred suchexciting pursuits over playing sports with the otherlads, or even getting home in time for dinner!

At this stage of his early life, Joseph’s parents dif-fered concerning what career he should pursue. Hisfather favored art, with heavy emphasis on the practi-cal profession of sign-painting; his (step)mother con-sidered a medical career more appropriate. Fortu-nately, his mother’s view prevailed. At the tender ageof 17, Joseph enrolled in the medical school of theUniversity of Pennsylvania, whose buildings of thattime were located not far from his home, and receivedhis M. D. degree in 1844 (with a thesis entitled “TheComparative Anatomy of the Eye of Vertebrated Ani-mals”). His medical training cost his parents some$140 per year but, as a quite comfortably living mid-dle-class family, they managed to make the payments(yet they might well have been distressed if they couldhave predicted that, only two years out of his M. D.,young Joseph would be completely abandoning anyactive practice of medicine!). While doing not badly inhis studies, especially in preparing anatomical dissec-tions and in producing highly accurate drawings,Joseph Leidy still voraciously pursued his own inter-ests as a mostly self-taught naturalist, enhanced byhis having been introduced to an unusually good mi-croscope by one of his perceptive mentors and soonthereafter given one as a birthday present by hisequally perceptive mother. This instrument allowedhim to note and describe cytological and histologicaldetails not stressed in his formal course work and, ofcourse, opened the way for his subsequent protisto-logical revelations, to which we return below. In fact,Leidy was the first American to seriously and exten-sively apply microscopy in biological and medical re-search. It was also while he was a medical studentthat he first met the famous British geologist CharlesLyell [1797–1875] when the latter gave some lecturesin Philadelphia; the two became instant friends andmutual supporters (of each other and of Charles Dar-win) and got together whenever both were in eitherAmerica or England at the same time.

Eugène Penard (Fig. 2) was born in Geneva, in thepredominantly French-speaking section of Switzer-land, on 16 September 1855; and – like several gen-erations of his direct ancestry – he was a patriotic“citoyen gènevois” throughout his lifetime. Unlikehis fellow “amoeba” man Joseph Leidy, however, hewas more frequently absent from his home town andfor longer periods of time.

The first Monsieur Penard (that we know about)established himself in Geneva back in the middle ofthe 14th century. This man and a number of his de-scendants were watchmakers and engravers, nottoo unusual a profession for Swiss men possessedof the requisite ability to do such precise work. Eu-gène’s adventurous grandfather left his wife andchildren (in Switzerland) to pursue such a career inAmerica; but his father was director of a privateschool in Geneva and did not follow in the footstepsof his own errant papa.

We know little about Eugène’s early childhood,but he studied at the Collège de Genève and, at age17, accepted a job as a cashier in a bank. Puzzlingly(to me), he remained in that profession for nearlynine years. But, apparently, he and his parents even-tually realized that he had abilities (latent and other-

Two Most Remarkable Amoeba Men 71

Figure 2. Eugène Penard, D.Sc. (1855–1954), in hislate nineties (ca. three years before his passing). [Pho-tograph from the author’s private collection]

wise) beyond such mundane work. He next wentabroad for a year or so, renewing his scholastic pur-suits, first at the University of Edinburgh, in farawayScotland, and then at Heidelberg (in Otto Bütschli’slaboratory), in nearby Germany. His studies, atwhich he excelled, included – among other subjectsas well – Latin, Greek, Greek Philosophy, Geology,and French Literature. He had already mastered theFrench, German, Italian, and English tongues; andhe was soon to add Russian to his linguistic reper-toire.

Returning to his home country in 1882, Penardbecame a zoological student of Karl Vogt[1817–1895], erstwhile Professor at Giessen, Ger-many, a position from which he was none too gentlyremoved for having participated in the revolutionarymovement of the late 1840s. Embittered, Vogt washappy to have been offered a professorship by themore enlightened University of Geneva, and Penardwas an eager and able student. In 1887, the twospent several months at the rather newly foundedStazione Zoologica di Napoli, where Eugène – work-ing at the “Swiss table” in the laboratory – com-pleted an elegant investigation of sperm penetrationinto the sea urchin egg (a work, regretfully, neverpublished). In the summer of the same year, he stud-ied the dinoflagellate Ceratium hirundinella, submit-ting his results of that research as a (prize-winning)thesis to the University of Geneva, for which he wasawarded his Doctor of Sciences degree (in late1887).

We shall return in a subsequent section to Pe-nard’s fascinating stays in Russia during the years1883-1886 and 1892-1898, periods not coveredabove. Suffice it to mention here that, by his ownwords, he “spent not more than five minutes in mak-ing original microscopical observations” essentiallyduring his whole times there, due to the pressure ofhis official duties. Can the reader imagine what sortsof jobs could possibly completely isolate him fromthe pursuits with which he was destined to person-ally fall so deeply in love, commencing earnestly in1887 but soon – only five years later – to be inter-rupted again until nearly 1899?

Early Professional Work and First Protis-tological Publications

Tracing exact parallels in the developing lives of thetwo great “amoeba” men being briefly recalled inthis historical essay is rather difficult – though I be-lieve worthwhile – for at least five reasons: Leidy wasborn a whole generation (32 years!) before Penard;Penard’s life spanned nearly 100 years, Leidy’s only

68; Leidy entered the microscopic world much ear-lier (age < 20, while Penard’s was close to 30);Leidy’s first substantial protistological publications(occurring long after and/or amongst papers in othervastly different research fields) appeared when hewas still scarcely 30 years old, while Penard wasseveral years older than that when his first (the di-noflagellate) monograph was completed, and hewas essentially carrying out research solely in thefield of protistology; and, finally, Leidy published pa-pers involving description of protists up to and evenbeyond the year of his death, while poor eye-trou-bled Penard – under doctor’s orders – was obligedto totally give up use of the microscope at age 67:what a blow to a taxonomic protistologist, althoughhe lived on, in excellent health otherwise, until wellinto his 99th year.

Joseph Leidy was precocious both in becomingknown and respected professionally on an interna-tional level and in producing diverse works of medi-cal and broad zoological interest. By the time he hadreached the age of 25, he had already published wellover 30 papers, many as very brief notes in the Pro-ceedings of the Academy of Natural Sciences ofPhiladelphia, but others were several pages inlength and accompanied by excellent figures. Theamazing range of topics covered ran from the micro-anatomy of the human larynx and liver and tissuetransplantation experiments to description of newgenera and species of fossil mammals (including,among others, two rhinoceroses and the earlyAmerican horse), from the taxonomy of several newspecies of invertebrates to careful description oftheir helminth, fungal, and even some bacterial par-asites, and from observations on (and superb illus-trations of) the internal organs of snails and the ne-matocysts of Hydra to the crystalline bodies in tis-sues of certain plants! And works of a purely protis-tological nature were not long in forthcoming. Infact, by 1850, the same year in which he laboriouslyedited an American edition of the human anatomytext by the Britisher James Quain, M.D. (Leidy wrotehis own, far superior, text on the subject in 1861,with a greatly enlarged and revised 2nd edition in1889), he was describing new species of symbioticprotists among the gregarine sporozoa and the nyc-totheran ciliates.

Leidy’s habit of working six or even seven days aweek, and sometimes 20(!) hours a day, made allsuch accomplishments possible. Yet this highly fo-cused workaholic with an encyclopedic mind alsoalways found time to help other people, personallyanswering (by long-hand, of course) many hundredsof letters from folk with queries about all sorts ofnatural phenomena, unstintingly cooperating in es-

72 J. O. Corliss

tablishing new Philadelphian institutions or aca-demic departments that included emphasis onbasic biological subjects, and holding interestingconversations on the street with both uneducatedfishmongers (and identifying some of their unusualcatches for them in their market stalls) and Univer-sity administrators or high-society industrialists andtheir wives, all the while (appearing, himself, to be) arelaxed, cheerful, kind-hearted, leisurely person.

In 1853 (but submitted in finished form to thepublisher in 1851), Leidy’s succinct 68-page publi-cation, A Flora and Fauna within Living Animals,practically established his reputation as the “Fatherof American Parasitology” – even though he was notyet 30 years of age. Beautifully illustrated by 10plates of precise figures, the text went beyond theusual morphological descriptions, including lifecycle information and data on host-parasite interre-lationships as well. Leidy also supplied convincingproof of the falsity of the doctrine of abiogenesis orspontaneous generation (although generally onlythe well publicized later observations and postula-tions of Tyndall, Pasteur, Koch, and other Europeansare credited today with such a significant discovery.The French protozoologist Joblot and the Italianphysiologist Spallanzani, however, had also demon-strated it in the 18th century: see Cole 1926).

Even earlier than 1853, Leidy had observed thevery important nematode worm Trichinella spiralis asa parasite in pigs, and he correctly suspected that itmight cause the disease trichinellosis (still todaywidely – but mistakenly – called trichinosis, althoughit was legitimately so known in earlier times) in hu-mans if infected pork was insufficiently cooked be-fore being eaten.

Eugène Penard, delayed in starting his protisto-logical career until about 33 years of age, certainlymade up for lost time. He produced major papers onthe heliozoa in 1889 and 1890, following his doctoralthesis on Ceratium, and very soon had published hisfirst comprehensive (230-page) monograph on therhizopod amoebae of fresh water (Penard 1890c)and a sizable work on the dinoflagellates of LakeGeneva (Penard 1891a); not much later (1893), hispaper on the lobosean amoeba Pelomyxa.

In 1891, by coincidence the very year of Leidy’spassing, Penard published a paper in the AmericanNaturalist, in English, on his findings of testaceousor thecate rhizopods, some new to science, in theRocky Mountains of Colorado, which he exploredpersonally for several months during a visit to Amer-ica (see below). As he told me with a certain amountof unconcealed delight when I visited him, some sixdecades later in Geneva, he had climbed the Rock-ies to 12,500 feet for his highest collection site, bet-

tering Leidy’s record by some 2,500 feet! He was agreat admirer of Leidy, but his own descriptionswere even more detailed and he was less cautiousabout describing new genera and species. He alsopaid more attention to the rules of the internationalzoological nomenclature, although, in all fairness tothe American, there were none in force at all until1842, when they were highly voluntary; and the fore-runner of the present obligatory Code (the ICZN) didnot come into existence until 1889 (see Ride 1999).

Penard’s figures were painstakingly precise, nodoubt reflecting an ability inherited from watch-making forebears, but lacked some of the artistry re-vealed in the Philadelphian’s magnificent coloredplates. At age 96, he apologized to me for the often“sketchiness” of his own line drawings in many ofhis monographs; but they were always exceedinglyaccurate and were almost always made from living,unfixed organisms. Furthermore, a naturalist en-dowed with artistic talent, Penard also produceddrawings of scenic landscapes, especially of un-usual sights during trips away from home. I’mpleased to be possessor of one of these, a view ofGold Hill, Colorado.

Penard’s reputation was well established throughhis early publications, but was even further en-hanced as his protistological career continuedapace (after another hiatus of some six yearsabroad: see below). Like Leidy, he remained a mod-est man while obviously a person of great energy,drive, skill, and dedication to any research projectthat he chose to pursue. Never a user of the oil im-mersion lens on his monocular microscope, his eye-sight must have indeed approached that of hisrenowned predecessor Leeuwenhoek. Attesting tothat is his early detection, 115 years ago, of the truenature of the second flagellum in dinoflagellates;and, some 80 years ago, of the presence of the re-duced second flagellum of Astasia and of the deli-cate caudal cilium of certain ciliates, the latter or-ganelle sometimes today practically requiring phaseor even electron microscopy to clearly demonstrateits existence.

Travels Away from Home Bases

Joseph Leidy, at a time in America’s scientificgrowth when such scholastically talented youths ashe were typically sent off to the great European uni-versities for proper training in their research special-ties, quietly chose to remain in Philadelphia. His aimin life seemed to have been to discover and de-scribe (new) biological facts with precision (and en-joyment!), while well aware of the relevant informa-

Two Most Remarkable Amoeba Men 73

tion available in the burgeoning European literature,and not to worry about speculation, competition, orfame. As he bluntly (rather stubbornly?) stated in thepreface of one of his paleontological monographs(Leidy 1869), “The present work is a record offacts… No attempt has been made at generaliza-tions or theories which might attract the momentaryattention or admiration of the scientific community.”Yet so voluminous and accurate were his observa-tions that other great 19th century biologists of theworld were soon getting in touch with him for furtherdata, many of which supported their own ideas: anoutstanding example was Charles Darwin (others, indue time, included renowned paleontologists,human anatomists, and parasitologists).

Nevertheless, Leidy – but usually only after strongurgings of colleagues – did venture outside Philadel-phia on occasion: to other parts of the ever-expand-ing USA and overseas.

At the age of 25, he accompanied his Universityof Pennsylvania Medical School mentor Dr. WilliamHorner to Europe for a profitable period of severalmonths (spring and summer of 1848). His name andreputation (already!) had preceded him and he wascordially greeted by such eminent (or soon to be-come eminent) scientists as – among still others –Charles Darwin, Charles Lyell, Richard Owen, andJohn Tyndall in England; Claude Bernard, H. Milne-Edwards, and C.-E. Blanchard in France; K. M.Diesing, Johannes Müller, C. T. E. von Siebold, R. A.von Kölliker, and T. Bischoff in Germany; and KarlRokitansky in Austria. His and Horner’s scientificand social calendar on the trip was hardly that of theordinary tourist! They visited innumerable museums,colleges, herbaria, botanical gardens, hospitals,medical research laboratories, libraries, governmentbuildings (e.g., Houses of Parliament), shops, book-stores, and microscope companies as well as artgalleries, castles, cathedrals, churches, country-sides, parks, operas, ballets, playhouses, and the-atres, not to mention residing in elite hotels and din-ing in the best of restaurants. Their days and nightswere fully occupied through the beneficent arrange-ments made by new-found friends and hosts.

Two years later (in the summer of 1850), per-suaded to accompany Dr. George B. Wood thistime, Leidy returned to Europe, officially mostly tocollect specimens, wax models, microscopes,charts, drawings, and books for medical schoolteaching needs. The trip was of slightly shorter du-ration but still covered some of the same activities(including meeting Owen and others again) and wasa strenuous one; but Joseph returned in a betterstate of health than when he had set out on the voy-age. His overseas colleagues were obviously im-

pressed by his top-quality research productivity, in adiversity of fields, during the interim ‘twixt his twovisits. One can imagine the thoughts that ranthrough many of their distinguished gray heads: howamazing for an American, and a mere lad, still, atthat!

Leidy was too busy with fossils in 1858 to crossthe Atlantic to carry out another planned trip abroad,so it wasn’t until 1875 that he journeyed again toLondon and Paris (with touristy side trips to Geneva,Brussels, and major cities in Germany), this time ac-companied by his delighted wife Anna. Nonethe-less, he again managed to make many professionalvisits and meet old acquaintances, plus acquiringnew friends in high scientific positions. One of themajor highlights for him was a long meeting with an-other admirer of his, T. H. Huxley, the great Britishnaturalist, part-time protozoologist, and evolution-ary biologist (well known as “Darwin’s bulldog”).Leidy, still interested in gems and rocks, also visiteda number of distinguished geologists and mineralo-gists. At their request, he later arranged to have sentto the British Museum several shipments of invalu-able specimens from the American Western Territo-ries.

His final brief trip abroad, accompanied by hisfaithful wife and his loving (adopted) daughter All-wina, was in 1889, a scant two years before hisdeath. He was in rather poor health himself, andthen aboard ship poor Anna came down with ty-phoid fever, which obliged them all to spend a num-ber of weeks in London, with husband and daughterliterally hovering anxiously over her sick bed. Fortu-nately, receiving the best medical care available,Anna recovered and they later journeyed on to Paris.Joseph, now a rather tired old man, again broughtback to Philadelphia specimens, etc. from variousmuseums; but the whole excursion ended up beingan exhausting one.

Although Leidy, “the Father of American Paleon-tology,” described – from tons of material – speci-mens representing more than 300 important newspecies of animals ranging from invertebrates tofishes, dinosaurs, and mammals, he seldom col-lected the fossils in person. Bones, teeth, scales,etc. were sent to him by eager collectors from allover the United States. However, he did make a fewtrips himself, most notable ones to the American farwest in the summers of 1872, 1873, 1877, and alongthe eastern coast (far up into Canada) in 1874. Healso, everywhere, collected Indian artifacts, miner-als, plant specimens, insects and other inverte-brates, parasitic material, and rhizopods! See thefollowing section for more information on Leidy’spaleontological contributions.

74 J. O. Corliss

Eugène Penard was much more adventurous withrespect to roaming away from his comfortable resi-dence, in Geneva. In fact, during most of the years1881–1898, he was living in other countries. Asmentioned above, he studied for a while (in1881–1882) outside Switzerland – in England andGermany – after his bank job; and then, a year or solater, he embarked on his first Russian adventure.He had applied for the position of tutor (perhaps en-couraged by his schoolmaster father?) to the royalfamily of Prince Orloff; accepted, he spent most ofthe years 1883–1886 in that busy position.

In 1884, he managed to get in a trip to Algiers (per-haps with his Russian employer?). Penard was then29 years old; and, by chance, he fell into animatedconversation with the city’s archivist/librarian whilesearching for certain scientific books (biological?).Quite likely (I wish we knew for certain!) the matter ofprotozoa arose, although young Eugène’s doctoralresearches were still three to four years from realiza-tion. At any rate, the 42-year old librarian eventuallybade him “bon voyage” and the pleasant encounterended. Years later, Penard discovered that thefriendly “old” man had been none other than EmileMaupas, the French protistologist who, at the verytime of their meeting, was deep into the magnificentciliate researches – being carried out after work in alittle laboratory in his small Algerian apartment – thatwould bring him long-lasting fame (e.g., Maupas1888, 1889; and see Jennings 1929, and the briefaccounts in Corliss 1978–1979 and Nanney 1997)!

On return from Russia to Switzerland, and follow-ing his brief trip to Italy with his mentor Carl Vogt(see the preceding section), Penard departed forWiesbaden, Germany, for another tutorial job, thistime with the family of Baron Belevski (years 1887-1890). Making good use of his time, he did manageto publish, in German, some new observations onrhizopods from the area (e.g., see Penard 1890a,b).

In 1891, our busy traveling amoeba-man set outfor America, expecting to secure a teaching positionat Columbia University, New York City, for which hehad hopefully applied. Rejected and dejected, heaccepted an invitation to visit the University of Col-orado, where the first head of biology there, JohnGardiner, was a friend who had chanced to meethim in Geneva some years before. His fascinationwith the Rocky Mountains and their unique rhi-zopods, as mentioned in the preceding section ofthis paper, restored Penard’s spirits and, after sev-eral weeks, he returned to Geneva, although still ap-parently looking for employment.

Next occurred his third tutoring job, his second inRussia. Living with the family of Prince Youssoupoff(years 1892–1898), he had his hands full as a

teacher of young Felix Youssoupoff, who is espe-cially remembered for his part, later, in plotting theassassination of Rasputin. Penard’s return toGeneva this time was a doubly happy one: he wasdeparting Russia at a politically tumultuous time inits history and he was bringing back a wife, a lovelyRussian woman who had also been employed as amember of Youssoupoff’s household.

Any other, subsequent visits out of Geneva orSwitzerland were of much shorter duration and gen-erally of reduced significance to themes of the pre-sent account of Penard’s life and protistologicalworks.

Later Years and Accumulated Honors

At age 41, Joseph Leidy took a bride without break-ing stride. The marriage, coming in 1864, near theend of the Civil War, surprised friends and col-leagues who had not even been aware of acourtship in progress with the quiet, plump, moth-erly woman, daughter of a clergyman from Ken-tucky. Their marriage was a long and happy one.Childless, Joseph and Anna, in 1876, adopted acharming little girl, Allwina Franck, daughter of a col-league at U. Penn, when her parents both passedaway from a long shared illness. A student who, atthe time, was living in a room on the third floor of theLeidy house described the trio as always such “acharming happy family circle!” Leidy continued towork mostly from his home; his amazing powers ofconcentration let nothing that was going on aroundhim distract him in the least, at times when hethought he required such solitude. Nevertheless,when little Allie once suffered a severe bout of diph-theria, Joseph is said to have sat by her bedsidecontinuously for days and nights, neither sleepingnor eating (Warren 1998).

Indefatigable, Leidy in his middle years continuedto produce research papers and treatises while tak-ing on more and more outside responsibilities, serv-ing on the boards or directorships of numerous sci-entific, academic, and philanthropic institutions andorganizations in the greater Philadelphia area, ac-tively joining the faculty at nearby Quaker-foundedSwarthmore College (in addition to his U. Penn posi-tions), aiding in starting the Philadelphia Zoo (nowthe oldest in America), etc. He was a man who sim-ply didn’t know how to say, “No!” He even attendedsocial events (if associated with the above activi-ties); he was such an interesting and witty conversa-tionalist (“the last man who knew everything”: War-ren 1998) – as well as cutting an imposingly hand-some figure in evening wear – that everyone, espe-

Two Most Remarkable Amoeba Men 75

cially the ladies in attendance, always wanted to beseated alongside him at banquet tables.

Speaking of women, Leidy – contrary towidespread practices in those days (and, alas, evenuntil quite recent years: for the protozoological pic-ture, see Corliss 1993) – had no compunctionsabout having them in his classes in medical school,in institutes where he taught, or in the buddingSwarthmore College just outside Philadelphia. Ap-parently, he was never officially an adviser or men-tor, but – interestingly enough – one of his femalestudents in 1884, Adele M. Field (for 15 years a Bap-tist missionary in the Orient) was so inspired by hisdiscourses on rhizopod amoebae that she subse-quently studied and published papers on these pro-tists from collections made in China.

For the most part, Leidy’s enthusiastic attentionto vertebrate fossils during the 1850s, 1860s, andearly 1870s eclipsed his precise microscopical re-searches on protozoological, parasitological, andother materials during those decades, distressingworkers around the world in such fields (Ward 1923).The fossil work, however, earned him such titles asthe “Cuvier of American Paleontology” and broughthim much (additional) fame from abroad; but it isquite beyond detailed consideration in the presentpaper (he published nearly 2,000 pages on extinctforms, mostly to be found in these four weightymonographs: Leidy 1854, 1865, 1869, 1873). Per-haps the single most startling early paleontologicaland evolutionary discovery made by young Leidy (in1858) – and with a correct deduction about its nor-mal posture — was that of a nearly complete skele-ton from New Jersey of a 28-foot herbivorous duck-billed dinosaur (Hadrosaurus foulkii) deduced by thePhiladelphian to have been a biped, the first di-nosaur ever so described. When he announced thenews, most European paleontologists could/wouldnot believe it, but T. H. Huxley was overjoyed be-cause such a reptile supported his own idea on theorigin of birds from dinosaurs.

Following appearance of Leidy’s (1856) uniquepaper, “A Synopsis of Entozoa and Some of TheirEctocongeners” (a work containing descriptions of172 species of parasitic protozoa and worms, manynew), it had seemed that he was indeed leavingsuch a fruitful budding field, parasitology, forever(see the above paragraph). On subsequently return-ing largely to study of minute living forms, in the late1870s, it became quite clear that one of the primereasons for his eventual almost complete with-drawal from the enticing field of vertebrate fossils,sadly enough, was because it had become so unen-joyable, even distasteful, for him in America underits new domination (starting in the 1860s) by fierce

rivals of each other, Marsh of Yale and Cope of Penn(Leidy’s juniors by 8 and 17 years, respectively, andthe latter a student of his), who had became vitriolicin their heated rivalry and competitiveness, werepaying large sums for discovered/uncovered bones(which in the past had been saved by farmers andamateur collectors and obligingly sent free to Leidy),were pirating each other’s collections, rushing intopublication – even in daily newspapers – for priorityin describing new forms, etc., etc.

So, finally, we come to Leidy’s mammoth mono-graph, Fresh-water Rhizopods of North America,published in 1879 by the U. S. Geological Survey. Ithas become a classic because of the contents of its324 pages of text material and, perhaps even more,for its 48 large plates of nearly 1,200 exquisitely exe-cuted figures in color. In a rare display of pique, thegentle monographer complained that the lithogra-pher hired to prepare his art work for printing didn’tdo full justice to the original drawings, causing ananxious moment for editor F. V. Hayden. It has beensuggested that Leidy was a “naturalist-illustrator”while the much admired ornithologist Audubon[1785–1851] was an “artist-naturalist,” a neat dis-tinction between these two great men with respectto their professional lives and the emphasis shownin their artistic productions (Warren 1998).

The still authoritative rhizopod work portraysspecies of some 40 valid genera (conservativelyclaimed by Leidy to contain a total of ca. 80species), while also providing synonyms and othernomenclatural details concerning all forms studied.Modestly, he considered only a relatively few of hisdescribed organisms as new to science: later work-ers, including Penard, tended to split up many of histaxonomically lumped forms. Leidy’s material wascollected from sites along the shores of the AtlanticOcean and as far west as lands now recognized asthe states of Colorado, Nebraska, Wyoming, theDakotas, and Utah. Gathering material requiredsome trips out of Pennsylvania, although other peo-ple also sent collections (i.e., soil samples, etc.) tohim from time to time. Cystic as well as trophicstages were depicted.

The majority of Leidy’s descriptions were ofspecies belonging to genera (using names here thatare considered correct today) such as Amoeba, Di-namoeba, Endamoeba, and Trichamoeba amongthe naked amoebae; Arcella, Difflugia, and Eug-lypha, among test-bearing forms; and Actinophrys,Actinosphaerium, and Clathrulina, among the helio-zoa (e.g., see Figures 3 and 4, and the full color re-production of Leidy’s Amoeba proteus which adornsthe cover of this issue of Protist). Leidy’s splendiddescription (in both his text and figures) of the uni-

76 J. O. Corliss

Two M

ost Rem

arkable A

moeb

aM

en77

Figure 3. Illustration of species from several sarcodinid genera studied in detail by both Leidy and, a few years later, Penard. All drawings are taken fromLeidy (1879), where they appeared in natural colors, a tribute to Leidy’s artistic abilities. A. Amoeba proteus, perhaps the best-known “naked” rhizopodamoeba around the world. Its pseudopodia are of the thick lobopodium type. B. Euglypha acanthophora, a thecate or testaceous amoeba with regularlyarranged siliceous scales, several spines, and dichotomously branched filopodia. C, D. Also testate (chitinous), Arcella dentata and A. discoides haveslender lobopodia; body attached to test by ectoplasmic strands. E. Difflugia amorpha, with test composed of cemented sand grains, sometimes plus di-atom shells or other foreign bodies; simple cylindrical lobopodia, occasionally slightly branched. F. Clathrulina elegans, a heliozoan (actinopod sarco-dinid) with a brownish envelope perforated by numerous circular or polygonal openings, a long stalk, and numerous fine pseudopodia (of the axopodialtype) projecting radially through the pores of the test.

78 J. O. Corliss

BA

C D

versally familiar Amoeba proteus has been widelyhailed as the best unambiguous account of this or-ganism; fittingly, Leidy is given the authorship of itsname (and as he spelled it), as of 1879. As in thecases of many of his rhizopods, a very brief descrip-tion of the organism occurred in a note publishedbefore appearance of his monograph (in the case ofAmoeba proteus, in the year 1878), but subsequentworkers have universally prefer to cite “1879” as thedate of the origin of many such Leidyan names.Principally because of this supreme work, Leidy hasbeen given still another founder title, the “Father ofAmerican Protozoology.”

In 1881, Leidy’s small but ground-breaking book,The Parasites of Termites, appeared, largely featur-ing the many symbiotic flagellated protists andbacteria in the gut of the wood-eating hosts. Hehad always planned, some day, to publish a majortreatise on all of the parasites (cestode, trematode,and nematode worms, insects and arachnids, bac-teria and protists such as amoebae, flagellates, andciliates) that he had described briefly and prelimi-narily over the years, but he never succeeded incarrying out this ambition. Fortunately, his brotherPhilip’s son – named Joseph Leidy, II and alsocalled Joseph Leidy, Jr. – edited a 281-page bookpublished in 1904 by the Smithsonian Institution(Researches in Helminthology and Parasitology)that is essentially a collection of the notes and pa-pers and illustrations (some never published else-where) of his uncle’s works in parasitology: this, toa degree, fulfilled (the first) Joseph Leidy’s dream inthis field of research.

Following his stressful last trip to Europe, in 1889,poor Leidy never fully recovered his health. In spiteof that, he insisted on maintaining his heavy sched-ule as director, head, professor, etc.(!) of various in-stitutions and colleges, and on carrying out addi-tional researches which increased his “great inven-tory of Nature” (Glassman et al. 1993). In fact, in theshort period 1889-1891 (recall that he passed away

on 30 April 1891), he continued to “leap hedges,”publishing notes and papers on topics as diverse asgregarine protozoa (with many additional observa-tions never completely finished: but see Crawley1903 for some of Leidy’s new species), boringsponges, parasitic copepods, ticks, ichneumonflies, avian parasites of the Little Blue Heron, thesabre-tooth tiger and Hippotherium and Rhinocerosfrom Florida, fossil human bones, and an extinctgenus allied to the peccaries. And he brought outthe 2nd edition of his textbook on human anatomy atthe same time! Also see a posthumous paper (Leidy1896), which included further data on fossil verte-brates from Florida. Altogether, over some 47 yearsof active research, our prolific naturalist authoredmore than 600 publications involving some 2,500species, a goodly number of which were new to sci-ence.

Leidy’s honors were many, and certainly not lim-ited to the inscriptions, statue (designed by SamuelMurray, a student of the renowned painter andsculptor Thomas Eakins), portraits, named streetsand laboratories and buildings, etc. to be found inhis home town of Philadelphia. But also not to beneglected is mention of the coveted Joseph LeidyMedal, struck in 1923 by the Academy of NaturalSciences of Philadelphia (an organization founded in1812, eventually publisher of its own journal, andwhich bestowed lifelong membership on Leidy in1845) to commemorate the centenary of the birth oftheir most distinguished member ever. The medal isawarded every three or four years “to honor excep-tional exploration, research, discovery, and publica-tion in a wide range of scientific disciplines.” Its firstrecipient, the only protistologist ever to receive it todate, was Herbert Spencer Jennings [1868–1947],famed for his research on behavior and evolution ofunicellular organisms (including rhizopod amoebae)and, later, on genetics of the ciliate Paramecium (seeSonneborn 1975). Not surprisingly, Jennings was anadmirer of both Leidy and Penard.

Two Most Remarkable Amoeba Men 79

Figure 4. More sarcodinids described or redescribed by Leidy and Penard, with figures all from Leidy’s (1879) col-ored renditions of the organisms. A. The common freshwater heliozoon Actinosphaerium eichhornii: relatively largebody, multinucleate, many radiating axopodia, feeds mostly on diatoms and other algal protists, occasionally a ro-tifer; ectoplasm and endoplasm both highly vacuolated, with vacuoles larger in the former. B. Trichamoeba villosa,a large naked amoeba characterized by its one to several broad lobopodia and a semi-permanent uroid with poste-riorly projecting fine filaments or “villi”; clear ectoplasm, one nucleus, one contractile vacuole, several food vac-uoles. C. Baileya mutabilis, a thecate rhizopod with a clear and flexible test and long filopodia that may branch,cross, and/or even anastomose. Single contractile vacuole. D. Dinamoeba mirabilis, a naked amoeba with numer-ous long, clear, conical/tapering lobopodia that twist or coil in retraction. Entire body surface often “bristles” with acovering of attached bacteria. (As is also true of figures A–F of my preceding Figure 3; figures A–D here have beenretouched slightly to aliminate disconcerting pseudopodia – coming from other (neighboring) figures on Leidy’soriginal plates – that have invaded the space occupied principally by the organism specifically being portrayed).

Leidy received an honorary doctorate fromFranklin and Marshall College in 1869, and fromHarvard University in 1886. In 1880, the Boston So-ciety of Natural History bestowed the annual WalkerGrand Prize on him. He was among the 50 leadingmen of science to establish the National Academyof Sciences in 1863. From abroad, in addition to in-vited membership in various long-distinguished so-cieties, he was elected to honorary membership inthe Royal Microscopical Society of London in 1879and in the Zoological Society of London in 1883. In1884, the Geological Society of London awardedhim its Lyell Medal; and, two years later, the Instituteof France bestowed its Cuvier Prize Medal on him.Finally, mention should be made of taxonomicnames, patronyms, created in his honor. For exam-ple, some gregarine sporozoa from crickets havebeen placed in the genus Leidyana Watson, 1915, agroup now with its own familial name, LeidyanidaeKudo, 1954; and Leidyella Jung, 1942, was pro-posed for a genus of testaceous rhizopod amoe-bae, but has been little used since. The genericnames Leidyonella and Leidyopsis were at one timesuggested for one of Leidy’s species of a parasiticflagellate in termites, but Kudo (1966) considersthem to be junior synonyms of Trichonympha Leidy,1877.

Although I have decried the fact that JosephLeidy seems little remembered personally today,there were many eulogies delivered – internationally– around the time of his passing (year 1891), and thegreat paleontologist Henry Fairfield Osborn eventu-ally produced a glowing report in his biographicalmemoir for the National Academy of Sciences (Os-born 1913). On the centenary of his birth, W. S. Mid-dleton, M.D. (1923) praised him mightily in the An-nals of Medical History, as did H. B. Ward, Ph.D.(1923) in the Journal of Parasitology (a journalfounded by Ward who, himself, has often beenhailed as the “Father of American Parasitology,”which would make Leidy the “Grandfather”?). Andrecall the book of Leidy’s parasitological notesedited by his nephew (Leidy, Jr. 1904).

On/near the centenary of Leidy’s death, SusanGlassman et al. (1993) published a fine honorificwork, in Philadelphia’s own Proceedings of theAcademy of Natural Sciences, including an Ap-pendix on the number of genera and species heworked with from each of the major taxa of organ-isms. D. H. Wenrich, parasitologist and protozoolo-gist, an illustrious 20th century successor of Leidy’sin Zoology at the University of Pennsylvania, hadamassed copious data on his celebrated predeces-sor with the intention of publishing a lengthy biogra-phy; alas, his plans were interrupted by his own sud-

den passing, in 1968, at the age of 83. Finally,Leonard Warren, M.D., Ph.D. (1998), Professor atboth the Wistar Institute and (emeritus) U. Penn, hasproduced the first long-awaited full-length biogra-phy (303 pp.) of Leidy, truly a sensitive and under-standing masterpiece.

At age 43, Eugène Penard brought back a bridefrom Russia. It is interesting to note that his age wasalmost the same as that of Leidy’s when the lattertook the same matrimonial plunge. M. et Mme Pe-nard remained a happy couple until her passing, atage 89, in 1945: 47 years together compared withLeidy’s 27 years of marital bliss, since the Americanrhizopodologist died at the relatively tender age of68. Back to another parallel: the Penards apparentlyhad no children of their own.

Penard’s active protistological research years,1888–1922, quantitatively about matched Leidy’snon-paleontological total because, although theGenevan still had the last third of his (considerablylonger) life to go, his eyesight fatigue brought practi-cally to a halt all detailed microscopical work be-yond 1922.

Penard’s second major monograph on free-livingamoebae, after the earlier one of 1890 cited in a pre-ceding section of this paper, came out nine yearslater (Penard 1899); the depths of Lake Genevaserved as the collecting site this time. It was quitesoon followed – with several shorter importantworks in between – by his huge (714 pages!) Faunerhizopodique du bassin du Léman (Penard 1902), amost authoritative taxonomic-ecological survey withmany new species described in greater detail thanthat ever seen in most older works, includingLeidy’s. In a complimentary way, the Swiss protistol-ogist might be referred to as a master of minutiae.

Penard’s first monograph on the freshwater“héliozoaires” appeared in 1904, quickly followed bytwo on the “sarcodinés” sensu lato (Penard1905a,b). During the same and the next seven years,a considerable number of additional substantialworks (some on edaphic and terrestrial as well asaquatic forms) appeared, including observations onmaterial collected (or sent to him) from such sites asneighboring countries, the British Isles (including thecelebrated Loch Ness, home of the alleged “mon-ster,” in Scotland), Colombia (via a German expedi-tion to South America), the Himalayan mountains ofIndia, and South Pole regions (collections of materi-als gathered during early Antarctic expeditions car-ried out by both British and French explorers). Sucha fantastically busy microscopist was this humblerhizopodologist!

In 1914, in the 60th year of his life, the seeminglytireless (à la Leidy!) Penard commenced his prolific

80 J. O. Corliss

series of investigations on predominantly freshwaterfree-living (free-swimming or attached to some livingor inanimate substrate) ciliated protozoa, includingthe suctorians (then considered a high-level sepa-rate taxonomic group, the Tentaculifera: see Corliss1979). The year had actually started, however, withan account on the rotifers of Switzerland, including adescription of several new species of these tiny mi-crometazoan organisms. The protozoan researchesessentially culminated in a monographic paper onthe suctorians (Penard 1920) and a monographicbook on the “regular” ciliates (Penard 1922a); thelatter included a detailed treatment of some 300species of which 168 were new. In between theseauthoritative publications, Penard (1921) managedto complete a paper on flagellates which appeared(by invitation, perhaps?) in the Proceedings of theAcademy of Natural Sciences of Philadelphia, a fa-vorite outlet of Leidy’s, as the reader will recall.

By the end of the year 1922, Penard had pub-lished some 2,150 pages (exclusive of plates of fig-ures) on the protozoa (primarily sarcodinids) in hiseight major monographs alone! His total number ofscientific publications, spanning his less than 30years of active research on microorganisms, comesto ca. 78 (eight each in German and English, the re-mainder in French). The total number of protistspecies he described as new amounts to ca. 530,with slightly over 62% being sarcodinids (Deflandre1958). Like Leidy, Penard worked mostly at thespecies level; neither of them described very manynew genera, usually content to stretch the bound-aries of the well known genera of such authoritativepredecessors as Ehrenberg, Dujardin, and Hertwig.

As mentioned earlier, the medically enforced re-tirement as a microscopist obliged Penard at age 67– but more than 30 years from the eventual date ofhis demise – to give up his passionate activity as anastute observer of living protists. Presumably, hetook this pronouncement philosophically and good-naturedly. He turned to writing some review articlesand some more (the first ones had appeared in1905) adventure and natural history novels andbooks for young people (for the last one, see Penard1946); and he re-arranged his many boxes of slidesof type-material of the numerous new species (seeabove) he had described. These slides, mostly ofcarmine-stained sarcodinids and ciliates, numberwell over one thousand and are to be found todaydistributed among three major museums of naturalhistory, all in Europe: the ones in London, Paris, andGeneva. In 1952, I examined some of these myself(as had Georges Deflandre before me: see Deflandre1954, 1958) and was amazed at their clarity despitetheir ages of 30-50 years or more!

Penard (1940–1941) also entered the realm of an-imal psychology, attributing behavioral traits to pro-tists: for example, instinct and memory. Some ofsuch investigations/thoughts on these possiblecharacteristics of protozoa are perhaps best suc-cinctly summarized in one of the suppositions pro-posed in his last paper, written in English and enti-tled Habituation (Penard 1947), which may be para-phrased as follows: the protozoa know what theyare doing! One of his examples: loricate ciliates(under microscopical examination) will quickly with-draw/contract into their tests when the coverslip islightly tapped; but that response lessens on re-peated tappings. This paper was preceded by twobooks by Penard (1922b, 1938) setting the stage forhis insightful entrance into the vast field of behaviorof “lower” organisms (recall Jennings 1904, 1931),which Penard felt was unfairly neglected by thegreat British psychologist W. H. Thorpe. Penard hadmet Jennings (his junior by some 13 years) once inEurope, around the turn of the century.

In 1945, following the death of his wife, Penard –at the age of 89 – moved into a rest home (princi-pally for elderly ladies, but he was deemed harm-less!?) on the outskirts of Geneva. He remained in-tellectually sharp, multilingual, and steady in voiceand writing hand, his weakened visual acuitynotwithstanding. Nine years later, on 5 January1954, he quietly passed away.

Recognition of Eugène Penard’s invaluable con-tributions to protozoology came to him at varioustimes in his long life. The Faculty of Sciences ofGeneva twice bestowed awards on him (in years1922, 1945), and he was elected to membership inleading biological (including the Société suisse deMicrobiologie) and natural history societies in hishome country. He held the office of President ofHonor of the Société suisse de Zoologie from 1936until his death. Though officially an amateur biolo-gist, he was accorded the fame and respect usuallyreserved for professionals (the category to whichJoseph Leidy and the great majority of renownedscientists over the ages have belonged).

Internationally, Penard was widely recognized aswell, principally for his abilities in microscopy in thestudy of living protozoological materials. He wasmade a (foreign) Fellow of the Linnean Society ofLondon and of the Royal Microscopical Society ofLondon, and a member of the renowned QueckettClub in London. He was early elected a Membred’Honneur de la Société française de Microscopie.In 1952, a scant two years before his death, he be-came the first Honorary Member of the young Soci-ety of Protozoologists, headquartered in Americabut international in membership (Corliss 1998). This

Two Most Remarkable Amoeba Men 81

last-mentioned honor pleased him mightily (Corliss1954). He penned a letter to me including thesetouching words, “This announcement was for me animmense satisfaction for such an honorable proof ofwhat I might have done in protozoan studies… Andit came from America!” Recall that 60 years earlierPenard had spent several enjoyable months collect-ing amoebae in the Rocky Mountains of the UnitedStates, his only trip to America.

Half a dozen generic names that honor the mod-est Swiss protistologist have been given to proto-zoa, five to rhizopod amoebae and one to a ciliate.In chronological order, they are Penardia Cash,1904, Penardiella Jung, 1942, Penardochlamys De-flandre, 1953, Penardogromia Deflandre, 1953, Pe-nardeugenia Deflandre, 1953, and EpenardiaCorliss, 1971. I like to think that the last, a replace-ment name for a ciliate first seen and well describedby Penard as a Glaucoma species always found inthe vicinity of the aquatic plant Myriophyllum, wouldhave evinced an amused smile from the good hu-mored Swissman because of the play on words in itsname: “epinard” is the French word for spinach.

To my knowledge, Penard – as a person – has re-ceived little attention of a biographical nature in theliterature since his passing in 1954. Aside from theshort necrological notices appearing at the time inseveral European journals, only the rather brief pa-pers of Deflandre (1954, 1958) and Corliss (1954,1956) mention aspects of his personal life while alsoemphasizing his importance to protozoology.

Concluding Comments

Both Joseph Leidy of Philadelphia and Eugène Pe-nard of Geneva were exemplary men in their displayof unbounded energy, incredible powers of concen-tration, high visual acuity, love for and amazingmemory of details, and unrestricted passion in pur-suit of “the lowly amoebae.” Above all, perhaps,they were humble non-fame-seeking naturalistswho, without the advantages of modern technology,turned their enthusiastic attention to the full bio-nomics (taxonomy plus ecology) of the rhizopodsarcodinids to the lasting benefit of protozoology.

Their personal lives, interesting though they mayhave been, are not as important to posterity, ofcourse, as their scientific contributions to the disci-plines or fields within which they worked. Many oftheir observations adding to “the great inventory ofNature” are not likely to be forgotten: consider thefact that such distinguished protistologists as R. R.Kudo [1886–1967], in the last edition of his widelyused textbook of protozoology (Kudo 1966), in-

cludes mention of 10 of Leidy’s genera and morethan two dozen of his species, and 15 of Penard’sgenera and nearly four dozen of his species, de-scriptions all originally made scores of years earlierand still holding up today. Specialists are familiarwith many more. Numerous books and compendiareproduce figures originally published by Leidy andPenard. Thus, one might conclude that their worksare nearly as immortal as the protists they studiedwith such earnest ardor and open admiration over100 years ago.

References

N.B. Included below, among the rest of the literature ci-tations, are only some 14 works by Leidy and twodozen by Penard, out of their numerous combinedtotal. Most of these are directly cited (in the custom-ary/conventional manner) on preceding text-pages,while a few are just indirectly referred to in the body ofthis essay but included here with the others for thereader’s interest. Not surprisingly, many of Leidy’s pa-pers, including major ones, are clearly of a non-protis-tological nature (see text). Data on numbers of pagesand figures are sometimes purposely supplied, espe-cially for Leidy whose works are often known for their il-lustrations.

Awerinzew S (1906) [Freshwater Rhizopoda] II. Trav.Soc. Nat. St. Pétersbourg 36 (2): 121–346 (in Russian)

Bary A de (1859) Die Mycetozoen. Z Wiss Zool 10:88–175

Blochmann F (1886) Die Mikroskopische Pflanzen- undThierwelt des Süsswassers. Braunschweig

Bovee EC, Jahn TL (1973) Taxonomy and phylogeny.In Jeon KW (ed) The Biology of Amoeba. AcademicPress, New York and London, pp. 37–82

Bütschli O (1880–1882) Protozoa. Abt. I. Sarkodina undSporozoa. In Bronn HG (ed) Klassen und Ordnung desTheir-Reichs, CF Winter, Leipzig, 1: 1–616

Cash J, Hopkinson J (1905) The British FreshwaterRhizopoda and Heliozoa. Vol. 1, Part I. Ray Society,London

Cash J, Hopkinson J (1909) The British FreshwaterRhizopoda and Heliozoa. Vol. 2, Part II. Ray Society,London

Cash J, Wailes, GH (1919) The British Freshwater Rhi-zopoda and Heliozoa. Vol.4. Ray Society, London

Cash J, Wailes GH (1921) The British Freshwater Rhi-zopoda and Heliozoa. Vol. 5. Ray Society, London

Cash J, Wailes GH, Hopkinson J (1915) The BritishFreshwater Rhizopoda and Heliozoa. Vol. 3. Ray Soci-ety, London

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Cienkowski L (1863) Das Plasmodium. Jahrb Wiss Bot3: 400–441

Claparède E, Lachmann J (1858–1861) Etudes sur lesInfusoires et les Rhizopodes. Mém. Inst. Nat. Genèvois.[Sole section on “les rhizopodes” is in Mémoire No. 6,pp 413–466]

Cole FJ (1926) The History of Protozoology. Universityof London Press, London

Corliss JO (1954) Dr. Penard and America. J. Proto-zool. 1: 191

Corliss JO (1956) Dr. Eugène Penard. Obituary. ProcLinn Soc London, pp 42–44

Corliss JO (1975) Three centuries of protozoology: abrief tribute to its founding father, A. van Leeuwenhoekof Delft. J Protozool 22: 3–7

Corliss JO (1978–1979) A salute to fifty-four great mi-croscopists of the past: a pictorial footnote to the his-tory of protozoology. Parts I and II. Trans Amer MicroscSoc 97: 419–458; 98: 26–58

Corliss JO (1979) The Ciliated Protozoa: Characteriza-tion, Clasification, and Guide to the Literature. 2nd ed.Pergamon Press, London and New York

Corliss JO (1992) Historically important events, discov-eries, and works in protozoology from the mid-17th tothe mid-20th century. Rev Soc Mex Hist Nat 42 (year1991): 45–81

Corliss JO (1993) The contributions of women to thescience of protozoology. Acta Protozool 32: 129–134

Corliss JO (1998) The golden anniversary of the Soci-ety of Protozoologists (1947–1997). J Euk Microbiol 45:1–26

Crawley H (1903) The polycystid gregarines of theUnited States. Proc Acad Nat Sci Phila 55: 41–58,632–644

Deflandre G (1953) Ordres des Testacealobosa (DeSaedeleer, 1934), Testaceafilosa (De Saedeleer, 1934),Thalamia (Haeckel, 1862) ou Thécamoebiens (Auct.)(Rhizopoda Testacea). In Grassé P-P (ed) Traité de Zo-ologie, Masson & Cie, Paris Vol 1, fasc 2, pp 97–148

Deflandre G (1954) Eugène Penard (1855–1954), sa vieet son oeuvre. J Protozool 1: 187–190

Deflandre G (1958) Eugène Penard (1855–1954) Corre-spondance et souvenirs. Bibliographie et bilan systé-matique de son oeuvre. Hydrobiologia 10: 1–37

Dobell C (1919) The Amoebae Living in Man: A Zoolog-ical Monograph. J Bale, Sons & Danielsson, London

Dujardin F (1841) Histoire des Zoophytes. Infusoires.Paris

Ehrenberg CG (1838) Die Infusionsthierchen als Vol-lkommene Organismen. Leipzig

Glassman S, Bolt Jr EA, Spamer EE (1993) JosephLeidy and the “Great Inventory of Nature.” Proc AcadNat Sci Phila 144: 1–19

Haeckel E (1878) Das Protistenreich… Günther, Leipzig

Haeckel E (1894) Systematische Phylogenie… I. Sys-tematische Phylogenie der Protisten und Pflanzen. GReimer, Berlin

Hertwig R (1879) Organismus der Radiolarien.Denkschr Med-Naturwiss Gesellsch 2: 1–227

Hertwig R, Lesser E (1874) Über Rhizopoden unddenselben nahestehende Organismen. Arch MicrosAnat 10 (Suppl): 35–243

Jennings HS (1904) Contributions to the study of thebehavior of lower organisms. Carnegie Inst Wash PublNo. 16: 1–256

Jennings HS (1929) Genetics of the Protozoa. BibliogrGenet 5: 105–330

Jennings HS (1931) Behavior of the Lower Organisms.Rev ed. Columbia University Press, New York

Joblot L (1718) Descriptions et Usages de plusieursnouveaux Microscopes… avec de nouvelles Observa-tions. Paris

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